Grinding wheel truing method and grinding machine for carrying out truing method

ABSTRACT

In a grinding wheel truing method of an aspect of the present invention, an outer peripheral surface of a grinding wheel is trued while a position of a truer with respect to the grinding wheel is moved from one end side toward the other end side in the axial direction of the grinding wheel. In the truing, a relative movement speed of the truer when a position of the outer peripheral surface of the grinding wheel which grinds a large-diameter portion of a conical surface of a work is trued is lower than a relative movement speed of the truer when a position of the outer peripheral surface of the grinding wheel which grinds a small-diameter portion of the conical surface of the work is trued.

TECHNICAL FIELD

An aspect of the present invention relates to a grinding wheel truing method and a grinding machine adopting the truing method.

BACKGROUND ART

Conventionally, works of various shapes are processed on a grinding machine. For example, as shown in FIG. 9, there is a work W including: a spindle portion WA; and a disc-shaped portion WB which has a flange-shape protruding from a substantially center of the spindle portion WA and in which at least the surface on one side in the axial direction is formed into a conical surface WC. The conical surface WC of the work W is ground by a disc-type grinding wheel TA by bring the disc-type grinding wheel TA into contact with the conical surface WC while the work W is being rotated about the axis.

The above-described grinding wheel TA is a so-called angular grinding wheel TA where, as shown in FIG. 9, a grinding surface TA1 on the periphery thereof is inclined with respect to a grinding wheel rotation axis ZTA and has a length substantially equal to the width of the conical surface WC. This angular grinding wheel TA is attached to a grinding machine and rotated about the grinding wheel rotation axis ZTA by the driving force of a motor or the like. Then, the work W is rotated about a work rotation axis ZW by another driving source and is ground by the grinding surface TA1 of the angular grinding wheel TA by bring the angular grinding wheel TA which is rotating into contact with the conical surface WC.

Here, when the conical surface WC of the work W is ground, between a conical surface WC1 on the side close to the work rotation axis ZW and a conical surface WC2 on the side far from the work rotation axis ZW, the circumferential speed is higher on the side far from the work rotation axis ZW. Consequently, the difference in diameter on the conical surface WC of the work W causes a difference in grinding removal amount, which causes a difference in the finished surface roughness of the finished work.

Moreover, the angular grinding wheel TA, which has a shape where the grinding surface TA1 is inclined with respect to the grinding wheel rotation axis ZTA, has a large-diameter portion TA3 where the diameter of the outer periphery is relatively large and a small-diameter portion TA2 where it is small. For this reason, on the grinding surface TA1 of the angular grinding wheel TA, the number of abrasive grains arranged in the circumferential direction of the large-diameter portion TA3 tends to be relatively larger than the number of abrasive grains arranged in the circumferential direction of the small-diameter portion TA2. Therefore, resulting from the fact that the small-diameter portion TA2 of the grinding surface TA1 of the angular grinding wheel TA processes the work W with a small number of abrasive grains compared with the large-diameter portion TA3, the finished surface roughness of the work W having undergone the processing tends to be large.

Here, in the grinding of the conical surface WC of the work W by the angular grinding wheel TA, a relationship occurs such that the large-diameter portion TA3 of the angular grinding wheel TA contacts the conical surface WC1 on the side close to the work rotation axis ZW and the small-diameter portion TA2 of the angular grinding wheel TA contacts the conical surface WC2 on the side far from the work rotation axis ZW. For this reason, the finished surface roughness of the finished conical surface WC of the work W is larger on the conical surface WC2 on the side far from the work rotation axis ZW due to a combination of the influence accompanying the difference in the circumferential speed of the work W and the influence accompanying the difference in the number of abrasive grains of the angular grinding wheel TA.

Here, the technique described in Patent Document 1 uses a grinding wheel that has a grinding surface smaller than the width of the conical surface of the work, and the grinding wheel contacting the conical surface is moved along the generating line of the conical surface to perform grinding. In this grinding, the finished surface roughness of the finished conical surface is attempt to fall within a desired tolerance by changing the rotation speed of the work.

RELATED ART DOCUMENTS Patent Documents

Patent Document 1: JP-A-2004-345054

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

However, according to the technique in Patent Document 1, processing of the conical surface takes time, so that processing cannot be performed efficiently. Accordingly, the inventors of the present application focus attention on a method for truing a grinding wheel by a truer that performs truing and dressing of a grinding wheel.

An aspect of the present invention has been made in view of such a point, and a problem to be solved is to reduce, when a conical surface of a work is ground, the difference in finished surface roughness between the conical surface on the side close to the work rotation axis and the conical surface on the side far from the work rotation axis, and process the work more efficiently.

Means for Solving the Problem

To solve the above-mentioned problem, the present invention includes a grinding wheel truing method and a grinding machine according the following aspects.

First, a first aspect of the present invention includes a grinding wheel truing method, in a grinding machine which comprises a grinding wheel having an axial length on an outer peripheral surface of the grinding wheel substantially equal to a length of a generating line of a conical surface of a work, and which grinds the conical surface of the work by bringing the outer peripheral surface into contact with the conical surface without relatively moving the grinding wheel in a direction of the generating line of the conical surface, for truing the grinding wheel using a truer, the grinding wheel for grinding the conical surface of the work by bringing the outer peripheral surface of the grinding wheel of the grinding machine into contact with the conical surface while rotating the work having the conical surface about the work rotation axis with respect to the work rotation axis, wherein, when the outer peripheral surface of the grinding wheel is trued while a position of the truer with respect to the grinding wheel is relatively moved along the outer peripheral surface of the grinding wheel from one end side toward the other end side in an axial direction of the grinding wheel on the outer peripheral surface of the grinding wheel, a relative movement speed of the truer when a position of the outer peripheral surface of the grinding wheel which grinds a large-diameter portion of the conical surface of the work is trued is lower than a relative movement speed of the truer when a position of the outer peripheral surface of the grinding wheel which grinds a small-diameter portion of the conical surface of the work is trued.

According to this first aspect, by changing the relative movement speed of the truer in performing truing, the surface condition of the grinding wheel can be changed. That is, the grinding surface roughness of the grinding surface of the grinding wheel that grinds the conical surface on the side far from the work rotation axis where the circumferential speed is high is made relatively smaller than the grinding surface roughness of the grinding surface of the grinding wheel that grinds the conical surface on the side close to the work rotation axis where the circumferential speed is low. Thereby, when the conical surface of the work is ground, the difference in finished surface roughness can be made smaller between the conical surface on the side close to the work rotation axis and the conical surface on the side far from the work rotation axis. Moreover, by making the axial length of the grinding wheel on the outer peripheral surface of the grinding wheel substantially equal to the length of the generating line of the conical surface of the work, when the outer peripheral surface of the grinding wheel is brought into contact with the conical surface and is ground, the grinding can be performed without relatively moving the grinding wheel in the direction of the generating line of the conical surface, so that the work can be processed efficiently. Therefore, when the conical surface of the work is ground, the difference in finished surface roughness can be made smaller between the conical surface on the side close to the work rotation axis and the conical surface on the side far from the work rotation axis, and the work can be processed more efficiently.

A second aspect of the present invention includes the rotary grindstone truing method according to the above-described first aspect, wherein the truer is relatively moved from the position of the outer peripheral surface of the grinding wheel which grinds the small-diameter portion of the conical surface of the work toward the position of the outer peripheral surface of the grinding wheel that grinds the large-diameter portion of the conical surface of the work, and the relative movement speed of the truer is gradually decreased, or wherein the truer is relatively moved from the position of the outer peripheral surface of the grinding wheel which grinds the large-diameter portion of the conical surface of the work toward the position of the outer peripheral surface of the grinding wheel that grinds the small-diameter portion of the conical surface of the work and the relative movement speed of the truer is gradually increased.

According to this second aspect, by gradually changing the relative movement speed of the truer in performing truing, the grinding surface roughness of the grinding wheel is gradually changed, so that the finished surface roughness of the conical surface of the work can be made more uniform.

A third aspect of the present invention includes the grinding wheel truing method according to the above-described first aspect or second aspect, wherein the grinding wheel is a cylindrical plane grinding wheel.

According to this third aspect, by the grinding wheel being the cylindrical plane grinding wheel, the difference in the number of abrasive grains arranged in the circumferential direction of the outer peripheral surface does not readily occur. For this reason, it is unnecessary to consider the difference in the density of the abrasive grains, and by adjusting the grinding surface roughness of the grinding surface of the grinding wheel, the finished surface roughness of the conical surface of the work can be adjusted, so that the finished surface roughness of the conical surface of the work can be made more uniform.

A fourth aspect of the present invention includes a grinding machine including: a grinding wheel; a truer that trues the grinding wheel; and control means, wherein the grinding machine carries out the grinding wheel truing method according to any one of the first aspect to the third aspect based on an instruction of the control means.

According to this fourth aspect, when the conical surface of the work is ground, a grinding machine can be obtained in which the difference in finished surface roughness can be made smaller between the conical surface on the side close to the work rotation axis and the conical surface on the side far from the work rotation axis and the work can be processed more efficiently.

Advantages of the Invention

According to aspects of the present invention, when the conical surface of the work is ground, the difference in finished surface roughness can be made smaller between the conical surface on the side close to the work rotation axis and the conical surface on the side far from the work rotation axis and the work can be processed more efficiently.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a grinding machine in the present embodiment.

FIG. 2 is a cross-sectional view of a work in the present embodiment.

FIG. 3 is a plan view showing a position at the time of grinding by a grinding wheel in the present embodiment.

FIG. 4 is a plan view showing a position in truing the grinding wheel in the present embodiment.

FIG. 5 is an enlarged plan view of part V of FIG. 4.

FIG. 6 is an enlarged cross-sectional view of the grinding wheel at part VI of FIG. 5.

FIG. 7 is a flowchart showing the procedure of processing by control means in the present embodiment.

FIGS. 8( a) to 8(c) are graphs showing changes of the relative movement speed of a truer in performing truing in the present embodiment, FIG. 8( a) is a first example of the change of the relative movement speed of the truer, FIG. 8( b) is a second example of the change of the relative movement speed of the truer, and FIG. 8( c) is a third example of the change of the relative movement speed of the truer.

FIG. 9 is a schematic view showing the example of grinding in the background art.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment the present invention will be described by using the drawings. In the drawings, the x-axis, the y-axis and the z-axis are orthogonal to one another, the y-axis indicates a vertically upward direction, the z-axis indicates the direction of the work rotation axis ZW which is the rotation axis of the work W, and x-axis indicates the reciprocating direction of a turning platform 12.

Next, using FIG. 1 to FIG. 8( c), a grinding machine 1 in the present embodiment will be described. A first embodiment is the grinding machine 1 where a plane grinding wheel TP (corresponding to the grinding wheel) is disposed in an appropriate position on the turning platform 12.

<General Structure of the Grinding Machine 1 (FIG. 1)>

As shown in FIG. 1, the grinding machine 1 is provided with a base 10, a main spindle table 11 capable of reciprocating in the z-axis direction on the base 10, and the turning platform 12 capable of reciprocating in the x-axis direction on the base 10, and the turning platform 12 is capable of turning about a turning axis ZS parallel to the y-axis. Control means (a numerical control device, etc.) for controlling movable members and the like is not illustrated.

The main spindle table 11 reciprocates in the z-axis direction by a z-axis drive motor 11 M and a feed screw, and the control means outputs a control signal to the z-axis drive motor 11M while detecting a signal from position detection means 11E such as an encoder, thereby performing positioning of the main spindle table 11 in the z-axis direction.

The turning platform 12 reciprocates in the x-axis direction by an x-axis drive motor 12M and a feed screw, and the control means outputs a control signal to the x-axis drive motor 12M while detecting a signal from position detection means 12E such as an encoder, thereby performing positioning of the turning platform 12 in the x-axis direction.

On the main spindle table 11, a main spindle platform 20 provided with a center member 21 and a tailstock 30 provided with a center member 31 are placed, and the center member 21 and the center member 31 are disposed on the work rotation axis ZW parallel to the z-axis direction. Moreover, on the tailstock 30, a truing device 25 for truing the plane grinding wheel TP is placed. (Depending on the arranged position relationship of the plane grinding wheel TP, the truing device 25 may provided on the main spindle platform 20.)

The center member 21 is provided on a main spindle 22, the main spindle 22 is provided with a non-illustrated drive motor, and the control means is capable of rotating the main spindle 22 about the work rotation axis ZW passing through the tip of the center member 21, up to a given angle at a given angular speed.

The center member 31 is provided on a tail spindle 32, and the tail spindle 32 is supported rotatably or unrotatably.

The turning platform 12 is in the form of a plate in order that it is smaller in size, and in the neighborhood of the center of the turning platform 12, a turning motor 13 is provided in such a manner as to protrude in the y-axis direction. The control means outputs a control signal to the turning motor 13 while detecting a signal from angle detection means such as an encoder, thereby controlling the turning angle of the turning platform 12.

On the turning platform 12, a plane grinding wheel device 50 provided with the plane grinding wheel TP (corresponding to the grinding wheel) is disposed in such a manner as to sandwich the turning motor 13.

A grinding wheel rotation axis ZTP which is the rotation axis of the plane grinding wheel TP is situated within a plane orthogonal to the turning axis ZS.

The plane grinding wheel TP is attached to an end portion in one direction in the direction of the grinding wheel rotation axis ZTP (in FIG. 1, the plane grinding wheel TP is attached to an end portion on the right side).

Moreover, the plane grinding wheel TP is rotated through a belt 50B from a grinding wheel drive motor 50M.

Moreover, although on the grinding machine 1, a coolant nozzle that supplies a coolant is provided in the neighborhood of the position of contact between the work W and the plane grinding wheel TP (the point of grinding), this is not illustrated.

As shown in FIG. 1, the plane grinding wheel TP has a grinding surface TP1 (corresponding to the outer peripheral surface of the grinding wheel) parallel to the grinding wheel rotation axis ZTP and is shaped like a cylinder.

In the plane grinding wheel TP, the axial length of the grinding surface TP1 which is the outer peripheral surface thereof is substantially equal to the length of the generating line WL (see FIG. 2) of the conical surface WC of the work W.

As shown in FIG. 3, the grinding machine 1 makes the conical surface WC of the work W grindable by bringing the turning platform 12 relatively close to the work W by turning the turning platform 12 so that the position of the grinding surface TP1 of the plane grinding wheel TP is the processing position of the plane grinding wheel TP that grinds the conical surface WC of the work W (the position where the grinding surface TP1 of the plane grinding wheel TP is brought into contact with the conical surface WC of the work W).

Although not shown, the work rotation axis ZW, the grinding wheel rotation axis ZTP and a truer rotation axis ZTR of the truing device 25 are disposed on a relatively moving plane orthogonal to the turning axis ZS.

<General Structure of the Work W (FIG. 2)>

As shown in FIG. 1, the work W has both end portions thereof (or the neighborhood of both end portions thereof) supported by the center member 21 and the center member 31 (a chuck may be used instead of the center members).

As shown in FIG. 2, the work W has a spindle portion WA and a disc-shaped portion WB protruding like a brim substantially in the center of the spindle portion WA and where at least a surface on one side in the axial direction is formed into the conical surface WC. On the disc-shaped portion WB, a small-diameter portion WBi is formed continuously from the spindle portion WA with a diameter Di, and a large-diameter portion WBo is formed continuously from the small-diameter portion WBi with a diameter Do in such a manner as to protrude like a brim. The conical surface WC is formed at an angle Wθ when viewed cross-sectionally. In this manner, the generating line WL is formed on the conical surface WC of the work W.

<Structure of the Truing Device 25 (FIGS. 1, 4 and 5)>

As shown in FIG. 1, the truing device 25 is for truing the plane grinding wheel TP and placed on the tailstock 30.

The truing device 25 has a truer TR rotated about the truer rotation axis ZTR parallel to the work rotation axis ZW and a non-illustrated drive motor that rotates this truer TR.

FIG. 4 shows a condition where the position of the truer TR with respect to the plane grinding wheel TP is relatively turned and moved into a truing start position A (see FIG. 5). That is, as shown in FIG. 5, the grinding machine 1 turns the plane grinding wheel TP by the turning platform 12 in such a manner that the grinding surface TP1 of the plane grinding wheel TP and a truer surface TR1 of the truer TR of the truing device 25 are situated substantially on the same straight line.

FIG. 5 is an enlarged view showing a condition where the plane grinding wheel TP is trued by the truer TR of the truing device 25. The truer TR has a substantially disc shape, and the outer peripheral surface thereof serves as the truer surface TR1.

Here, as a piece of knowledge of the grinding wheel of the grinding machine, there is a correlation between the grinding allowance cross-sectional area and the finished surface roughness of the ground processed surface of the work (the work W in the present embodiment). That is, there is a relationship such that the larger the grinding allowance cross-sectional area is, the larger (rougher) the finished surface roughness of the processed surface of the work is.

Moreover, as a piece of knowledge about truing of the grinding wheel of the grinding machine, there is a relationship such that the higher the movement speed of the truer with respect to the grinding wheel is, the larger the finished surface roughness of the processed surface of the work processed by the grinding wheel trued by the truer.

Based on these pieces of knowledge, in the truing of the plane grinding wheel TP, attention is focused on changing the speed of the truer TR.

<Processing Procedure of the Method for Truing the Plane Grinding Wheel TP (FIG. 7)>

Next, using the flowchart shown in FIG. 7, an example of the processing procedure of the method for truing the plane grinding wheel TP by the control means will be described. The control means executes the processing shown in FIG. 7 in cases such as when an instruction to execute truing is provided or when the preset truing timing comes.

At step S10, the control means relatively turns and moves the position of the truer TR with respect to the plane grinding wheel TP (the position shown in FIG. 4) so that the position of the truer TR with respect to the plane grinding wheel TP is the truing start position A, and proceeds to step S20.

At step S20, the control means sets the initial movement speed of the relative movement speed F of the truer TR with respect to the plane grinding wheel TP, and proceeds to step S30. For example, when the truing start position A shown in FIG. 5 is the side where the small-diameter WBi of the conical surface WC of the work W is ground (see FIG. 2), the initial movement speed is set to a speed relatively high compared with the movement speed of the side where the large-diameter portion WBo of the conical surface WC is ground (see FIG. 2), and when the truing start position A is the side where the large-diameter portion WBo of the conical surface WC of the work W is ground (see FIG. 2), the initial setting speed is set to a speed relatively low compared with the movement speed of the side where the small-diameter portion WBi of the conical surface WC is ground (see FIG. 2).

At step S30, the control means moves the relative position of the truer TR with respect to the plane grinding wheel TP at the set relative movement speed F to perform truing (the condition shown in FIG. 5), and proceeds to step S40.

At step S40, the control means detects the current relative position of the truer TR with respect to the plane grinding wheel TP, and proceeds to step S50.

At step S50, the control means determines whether the relative position of the truer TR with respect to the plane grinding wheel TP has reached a truing end position B (see FIG. 5) or not. When it has reached the truing end position B (Yes), the control means proceeds to step S70, and when it has not reached the truing end position B yet (No), the control means proceeds to step S60.

When proceeding to step S60, the control means sets the movement speed according to the position, returns to step S30, and repeats step S30 and succeeding steps. For example, when movement is being made from the side where the small-diameter portion WBi of the conical surface WC of the work W is ground to the side where the large-diameter portion WBo is ground, the movement speed is decreased gradually or in steps according to the position (see FIGS. 8( a) to 8(c)), and when movement is being made from the side where the large-diameter portion WBo of the conical surface WC of the work W is ground to the side where the small-diameter portion WBi is ground, the movement speed is increased gradually or in steps according to the position.

When proceeding to step S70, the control means turns or moves the position of the plane grinding wheel TP to the initial position (the position shown in FIG. 1) (returns it to the initial position), and ends the truing processing.

The change in the relative speed of the plane grinding wheel TP and the truing device 25 is made gradually or in steps. Here, although it is more desirable that the change in the relative speed F of the plane grinding wheel TP and the truing device 25 be changed successively according to the relative position of the truer TR with respect to the plane grinding wheel TP as shown in FIG. 8( a), the change may be made in steps every time the relative position of the truer TR with respect to the plane grinding wheel TP moves a predetermined distance as shown in FIG. 8( b), or may be made in two steps as shown in FIG. 8( c).

By performing the above-described truing, the grinding surface TP1 of the plane grinding wheel TP is brought into a condition where the protrusion amount of the abrasive grains gradually changes as shown in FIG. 6.

Regarding the protrusion amount H of the abrasive grains TP2 on the grinding surface TP1, truing is performed so that as shown in FIG. 6, the protrusion amount HA on the side where the small-diameter portion WBi of the conical surface WC of the work W is ground is large and the protrusion amount HB on the side where the large-diameter portion WBo is ground is small. In this way, the grinding surface roughness is adjusted.

As described above, according to the method for truing the plane grinding wheel TP (grinding wheel) and the grinding machine 1 for carrying out the truing method according to the present embodiment, by changing the relative movement speed of the truer TR in performing truing, the surface condition of the plane grinding wheel TP can be changed. That is, the grinding surface roughness of the grinding surface TP1 of the plane grinding wheel TP that grinds the conical surface WC in the position on the side far from the work rotation axis ZW where the circumferential speed is high (the side of the large-diameter portion WBo) is made relatively smaller than the grinding surface roughness of the grinding surface TP1 of the plane grinding wheel TP that grinds the conical surface WC in the position on the side close to the work rotation axis ZW where the circumferential speed is low (the side of the small-diameter portion WBi). By doing this, when the conical surface WC of the work W is ground, the difference in finished surface roughness can be made smaller between the position of the conical surface WC on the side close to the work rotation axis ZW (the side of the small-diameter portion WBi) and the position of the conical surface WC on the side far from the work rotation axis ZW (the side of the large-diameter portion WBo). Moreover, by making the axial length of the plane grinding wheel TP on the grinding surface TP1 (corresponding to the outer peripheral surface of the grinding wheel) of the plane grinding wheel TP substantially equal to the length of the generating line WL of the conical surface WC of the work W, when the conical surface WC is ground by bring the outer peripheral surface of the plane grinding wheel TP into contact with the conical surface WC, the conical surface WC can be ground without relatively moving the plane grinding wheel TP in the direction of the generating line WL of the conical surface WC, so that the work W can be processed efficiently.

Moreover, by gradually changing the relative movement speed of the truer TR in performing truing, the grinding surface roughness of the plane grinding wheel TP is gradually changed, so that the finished surface roughness of the conical surface WC of the work W can be made more uniform.

Moreover, by the grinding wheel being the cylindrical plane grinding wheel TP, the difference in the number of abrasive grains arranged in the circumferential direction of the grinding surface TP1 does not readily occur. For this reason, it is unnecessary to consider the difference in the density of the abrasive grains TP2, and by adjusting the grinding surface roughness of the grinding surface TP1 of the plane grinding wheel TP, the finished surface roughness of the conical surface WC of the work W can be adjusted, so that the finished surface roughness of the conical surface WC of the work W can be made more uniform.

Moreover, the grinding machine 1 can be obtained where when the conical surface WC of the work W is ground, the difference in finished surface roughness can be made smaller between the position of the conical surface WC on the side close to the work rotation axis ZW (the side of the small-diameter portion WBi) and the position of the conical surface WC on the side far from the work rotation axis ZW (the side of the large-diameter portion WBo) and the work W can be processed more efficiently.

While the embodiment of the present invention is described above, the grinding wheel truing method and the grinding machine for carrying out the truing method of the present invention is not limited to the present embodiment, and may also be carried out in various forms without departing from the scope of the invention.

For example, while in the present embodiment, the grinding wheel truing method is described with the plane grinding wheel TP as an example, the present invention is also applicable in the case of an angular grinding wheel.

Moreover, while an example where in the x-axis direction, the plane grinding wheel TP is movable with respect to the work W and in the z-axis direction, the work W is movable with respect to the plane grinding wheel TP is shown in the present embodiment, the structure is only necessarily such that the plane grinding wheel TP is relatively movable in the x-axis direction and in the z-axis direction (movable on the xz plane [corresponding to the relatively moving plane]) with respect to the work W.

Moreover, while regarding the grinding machine 1 described in the present embodiment, an example where the plane grinding wheel TP is provided on the turning platform 12 is shown, the present invention is not limited thereto, and a multifunction grinding machine where a plane grinding wheel and an angular grinding wheel are disposed in appropriate positions on the turning platform may be adopted. According to this, various portion other than the conical surface of a work can be ground.

While regarding the grinding machine 1 described in the present embodiment, an example where each grinding wheel is supported in a cantilever manner is shown, the grinding wheel may be supported in a double support manner.

The shape and structure of the grinding wheel and the shape of the work W are not limited to the ones described in the present embodiment.

The present application is based upon Japanese Patent Application (No. 2013-073593) filed on Mar. 29, 2013, the contents of which are incorporated herein by reference.

DESCRIPTION OF REFERENCE SIGNS

1: Grinding Machine

10: Base

11: Main Spindle Table

12: Turning Platform

13: Turning Motor

11M: Z-axis Drive Motor

11E: Position Detection Means

12M: X-axis Drive Motor

12E: Position Detection Means

20: Main Spindle Platform

21: Center Member

22: Main Spindle

25: Truing Device

30: Tailstock

31: Center Member

32: Tail Spindle

50: Plane Grinding Wheel Device

50B: Belt

TP: Plane Grinding Wheel (Grinding Wheel)

TP1: Grinding Surface (Outer Peripheral Surface of Grinding Wheel)

TP2: Abrasive Grain

H: Protrusion Amount

HA: Protrusion Amount

HB: Protrusion Amount

W: Work

WC: Conical Surface

WA: Spindle Portion

WB: Disc-shaped Portion

WBi: Small-Diameter Portion

WBo: Large-Diameter Portion

WC: Conical Surface

Di: Diameter

Do: Diameter

WL: Generating Line

Wθ: Angle

ZS: Turning Axis

ZW: Work Rotation Axis

ZTP: Grinding Wheel Rotation Axis

ZTR: Truer Rotation Axis

TR: Truer

TR1: Truer Surface

F: Relative Movement Speed

A: Truing Start Position

B: Truing End Position 

1. A grinding wheel truing method, in a grinding machine which comprises a grinding wheel having an axial length on an outer peripheral surface of the grinding wheel substantially equal to a length of a generating line of a conical surface of a work, and which grinds the conical surface of the work by bringing the outer peripheral surface into contact with the conical surface without relatively moving the grinding wheel in a direction of the generating line of the conical surface, for truing the grinding wheel using a truer, the grinding wheel for grinding the conical surface of the work by bringing the outer peripheral surface of the grinding wheel of the grinding machine into contact with the conical surface while rotating the work having the conical surface about the work rotation axis with respect to the work rotation axis, wherein, when the outer peripheral surface of the grinding wheel is trued while a position of the truer with respect to the grinding wheel is relatively moved along the outer peripheral surface of the grinding wheel from one end side toward the other end side in an axial direction of the grinding wheel on the outer peripheral surface of the grinding wheel, a relative movement speed of the truer when a position of the outer peripheral surface of the grinding wheel which grinds a large-diameter portion of the conical surface of the work is trued is lower than a relative movement speed of the truer when a position of the outer peripheral surface of the grinding wheel which grinds a small-diameter portion of the conical surface of the work is trued.
 2. The grinding wheel truing method according to claim 1, wherein the truer is relatively moved from the position of the outer peripheral surface of the grinding wheel which grinds the small-diameter portion of the conical surface of the work toward the position of the outer peripheral surface of the grinding wheel that grinds the large-diameter portion of the conical surface of the work, and the relative movement speed of the truer is gradually decreased, or wherein the truer is relatively moved from the position of the outer peripheral surface of the grinding wheel which grinds the large-diameter portion of the conical surface of the work toward the position of the outer peripheral surface of the grinding wheel that grinds the small-diameter portion of the conical surface of the work and the relative movement speed of the truer is gradually increased.
 3. The grinding wheel truing method according to claim 1, wherein the grinding wheel is a cylindrical plane grinding wheel.
 4. A grinding machine comprising: a grinding wheel; a truer that trues the grinding wheel; and a control device, wherein the grinding machine carries out the grinding wheel truing method according to claim 1 based on an instruction of the control means device. 